Cannot Login with a Admin portal -Error Code: 399287

Question

Hello Team,

I cannot login with my admin portal login, since i dont have MFA. I have tried login with my mobile number. Its shows an error message "Sorry, we're having trouble verifying your account. Please try again. with the Error Code: 399287"

Can you please assist on this.

Thanks in advance.

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Moved from: Microsoft 365 and Office | Subscription, account, billing | Other | Other

Answer 1

Hello @BATI SHOOR,

Thank you for reaching out to the Microsoft Q&A forum.

Based on the error message (Error Code: 399287), this typically indicates an issue with multi-factor authentication (MFA) or verification methods associated with your admin account. Since you mentioned that you do not have MFA configured and are unable to verify using your mobile number, this may happen in the following scenarios:

• The account previously had MFA enabled and the authentication method is no longer accessible
• Security defaults or Conditional Access policies are enforcing MFA
• The account is the only Global Admin and is now locked out

If there is another Global Admin in your tenant, please ask them to sign in to the Microsoft Entra Admin Center and reset your authentication methods or review MFA / Conditional Access settings for your account. However, if you are the only administrator in the tenant, this situation requires direct assistance from Microsoft Support, as verification-related issues cannot be resolved through the Q&A forum for security reasons.

Below are the available options:

Option 1: Contact Microsoft Support by phone

• You can find the customer service number for your country or region here: Customer service phone numbers

Option 2: Create a temporary tenant to submit a support request

If you are unable to reach support by phone, you may create a temporary Microsoft 365 trial tenant solely for the purpose of contacting support.

Alternatively, you can try set up a new trial tenant and submit your support request: 

• Visit the Microsoft 365 Enterprise Plans page: Go to Compare Office 365 Enterprise Pricing and Plans | Microsoft 365. 
• Choose a plan and start a free trial: Select any of the available plans and click "Try for free" to begin the trial setup process. 
• Follow the guided setup: Complete the steps to create a new Microsoft account and a new tenant. This will be a separate and independent Microsoft 365 environment. 
• Access the Microsoft 365 Admin Center: Once the new tenant is created, navigate to https://admin.microsoft.com/. 
• Go to Support: In the left-hand navigation menu, click on "Support" and then "Help & support." 
• Raise a support ticket: Describe your issue in detail. Crucially, you must clearly state that you are locked out of a different, pre-existing Microsoft 365 tenant where you are the administrator. Provide the following information about your locked account:  

  + Your administrator account email address for the locked tenant. 

  + The domain name of your locked tenant  

  + Any error messages you are receiving. 

  + Details about the authentication issues you are experiencing. 

  + Confirmation that you are the administrator of the locked tenant. 

• Submit your ticket: Follow the prompts to submit your support request. You will likely receive a ticket number for tracking. 

Important notes:  

• This new trial tenant will not give you access to any of the data or settings in your original locked tenant. It is solely a temporary means to contact Microsoft support. 
• Be prepared for Microsoft support to ask for verification of your identity and administrative rights for the locked tenant. 
• The resolution time might be longer as you are contacting support from a different tenant. 
• Remember to cancel the trial subscription for the new tenant once your issue with the original account is resolved to avoid any unintended charges. You can typically do this within the Microsoft 365 Admin Center under "Billing" > "Your products." 

Hope this answer can help you with your concerns.

Answer 2

Error code 399287 in this context indicates that the phone number used for SMS verification has been flagged with a “bad reputation” and is blocked for Microsoft Entra multifactor authentication (MFA). This is why sign-in via mobile number fails with “Sorry, we're having trouble verifying your account. Please try again.”

Because sign-in is blocked at the MFA step and this is an admin account, the resolution requires Microsoft support intervention; it cannot be fixed from the portal while locked out.

Use the following approach based on the scenarios in the references:

1. If there is another global admin in the tenant
   • Ask that admin to sign in to the Microsoft Entra admin center (https://entra.microsoft.com).
   • Go to Users → All users → select the affected admin account.
   • Open Authentication methods and choose Require re-register multifactor authentication.
   • Optionally, verify or update phone numbers in the user’s profile.
   • After this reset, sign in again and register MFA using a different method (for example, Microsoft Authenticator app or a different phone number) so that SMS to the blocked number is no longer required.
2. If this is the only global admin (no other admins available)
   • This scenario must be handled by the Microsoft Data Protection / Tenant Recovery team, as shown in multiple similar cases in the references.
   • Call Microsoft Support using the regional Customer service phone numbers - Microsoft Support listed in the documentation.
   • When prompted by the automated system, clearly indicate that this is an Authenticator/MFA issue for an Office 365 for business / company account, that the caller is the administrator, and that there is no other admin.
   • Ask the frontline agent to open a Data Protection / Tenant Recovery or similar ticket to:
     • Remove the “bad reputation” block on the phone number and/or
     • Reset MFA for the admin account so that new methods can be registered.
   • Be prepared to provide tenant-identifying information (tenant name, domain, admin UPN) and to complete ownership verification steps.
3. After Microsoft resets MFA or clears the block
   • Sign in again and complete MFA registration.
   • Add at least one additional verification method (for example, Microsoft Authenticator plus an alternate phone) to avoid lockout if one method fails.
   • If the original phone number was the cause (bad reputation), consider using a different phone number or primarily using the Authenticator app going forward.

In similar resolved cases, the Microsoft Data Protection team or Microsoft 365 Data Protection support reset MFA or cleared the block on the number, after which sign-in and MFA registration worked again.

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References:

• You don't receive a text or voice call that contains the verification code for Microsoft Entra multifactor authentication
• "We didn't receive a response" error message when you try to sign in by using Azure Multi-Factor Authentication
• Common problems with two-step verification for a work or school account
• "Account verification system is having trouble" error message when you try to sign in by using a work or school account
• "We could not verify your account" error when you try to reset your admin password in Microsoft 365, Intune, or Azure
• Microsoft Q&A Unable to Verify Identity for Azure Login – Error 399287
• Azure has blocked myphone number for SMS verification due to a “bad reputation” flag - Microsoft Q&A
• Global Admin Locked out - Microsoft Q&A
• I have a Micrsoft business account and I am the admin and the only user registered under this account. I can't log in because i have replaced my phone and the authenticator doesn't work. - Microsoft Q&A
• Microsoft authenticator sending me into a spiral - Microsoft Q&A